The present invention relates generally to valves, and more particularly, to the gate valves used to establish isolation between interfacing chambers.
Transport modules are generally used in conjunction with a variety of substrate processing modules, which may include semiconductor etching systems, material deposition systems, and flat panel display etching systems. Due to the growing demands for cleanliness and high processing precision, there has been a growing need to reduce the amount of human interaction during between processing steps. This need has been partially met with the implementation of transport modules which operate as an intermediate handling apparatus (typically maintained at a reduced pressure, e.g., vacuum conditions). By way of example, a transport module may be physically located between one or more clean room storage facilities where substrates are stored, and multiple substrate processing modules where the substrates are actually processed, e.g., etched or have deposition performed thereon.
In this manner, when a substrate is required for processing, a robot arm located within the transport module may be employed to retrieve a selected substrate from storage and place it into one of the multiple processing modules. As is well known to those skilled in the art, transport modules are generally employed to "transport" substrates among multiple storage facilities and processing modules in a "cluster tool architecture."
FIG. 1 depicts a typical cluster tool architecture 100 illustrating the various chambers that interface a transport module 106. Transport module 106 is shown coupled to three processing modules 108a-108c which may be individually optimized to perform various fabrication processes. By way of example, processing modules 108a-108c may be implemented to perform transformer coupled plasma (TCP) substrate etching, layer depositions, and/or sputtering. Connected to transport module 106 is a load lock 104 that may be implemented to provide substrates to transport module 106.
Load lock 104 may be coupled to a clean room 102 where substrates are stored. In addition to being a retrieving and serving mechanism, load lock 104 may also serves as a pressure varying interface between transport module 106 and clean room 102. Therefore, transport module 106 may be kept at a constant pressure (e.g., vacuum), while clean room 102 is kept at atmospheric pressure. To prevent leaks between modules during pressure varying transitions, or to seal off a processing module from transport module 106 during a processing, various types of gate drive valves are used to isolate the various modules. For more information on gate drive valves, reference may be made to U.S. Pat. No. 4,721,282, which is hereby incorporated by reference.
FIG. 2 is a three dimensional perspective of a conventional interfacing arrangement 200 having a valve body 205 positioned between a processing module 108 and transport module 106. As shown, valve body 205 has a valve drive assembly 206 positioned below valve body 205. Valve drive assembly 206 generally includes a number of mechanical interconnections, electrical connections and gas conduit networks designed to raise and lower a shaft 208 which is connected to a gate plate 210. As shown, valve body 205 includes two interface ports 216 which provide a passageway for substrates to be transported in and out of processing module 108. As can be appreciated, conventional cluster architectures typically suffer in having a large footprint when multiple valve bodies 205 are placed between modules that interface with transport module 106.
As is well known in the fabrication technology industry, clean room space is quite expensive to construct and maintain. Consequently, cluster architectures having large footprints disadvantageously drive up the costs associated with building and maintaining fabrication clean rooms. To combat this problem, gate drive body 205 and drive assembly 206 manufacture's have developed narrower and thinner housing structures. Although some dean room space is salvaged, the resulting housing structure is typically too weak to withstand periodic disassembly required to maintain and service gate drive body 205 and drive assembly 206.
By way of example, to establish a vacuum-tight seal between facets 212 of processing module 108 and transport module 106, O-rings 220 are conventionally sandwiched between processing module 108 and transport module 106. Typically, the modules are bolted together, pneumatics (e.g., air supply lines) and gas lines are connected and tested, electrical connections are connected and tested, and computer connections are made to various testing computers running testing software. Thus, modules 106 and 108 must be separated and these interfacing connections disconnected and then reconnected.
Also, an O-ring 221 located within valve body 205 will typically require periodic replacement. When this happens, a bonnet plate 222 must be removed from the bottom surface of valve body 205. However, if the chambers are not separated before removing bonnet plate 222, the forces exerted on valve body 205 by the adjoining modulus 106 and 108 will typically cause serious inward warping to valve body 205. That is, bonnet plate 222 generally provides the essential structural support to prevent the inward collapse of valve body 205. Therefore, if bonnet plate 222 is removed without complete disassembly, the reinstallation of drive assembly 206 and bonnet plate 222 will be very difficult since the original structural shape of valve body 205 will no longer be optimized to receive the internal components.
Consequently, the replacement of O-ring 221 as well as O-rings 220 will necessitate the disassembly of the entire system including mechanical interconnections and electrical contacts located inside of valve body 205 and drive assembly 206. In addition, additional warping may occur during disassembly, and the valve body may have to be replaced or faced-off at the expense of reduced throughput when the entire cluster architecture is down for repair.
In view of the forgoing, what is needed is a gate drive valve that provides suitable isolation between interfacing chambers without increasing the footprint of a cluster architecture and without sacrificing the structural integrity of the valve body and drive assembly.